The Program consists of four individual projects and a core facility. Eight investigators from five departments and three universities are contributing to the proposed projects. The fundamental points of emphasis are on the plasticity of the neuromuscular system in response to spinal lesions and the consequences of the plasticity or lack of it to locomotor capabilities. The experimental models to be used in addition to normal cats are: low thoracic complete spinalization, surgical isolation of the lumbar cord, partial deafferentation, partial denervation of muscle, self-reinnervation of muscle, and surgical removal of synergistic muscles. Variations of these models include three forms of training, passive hindlimb oscillation and static posture maintenance of spinalized cats and hindlimb oscillation of spinally isolated cats. The plasticity of movement control will be studied at the systemic level by carefully assessing force, velocity, length and electromyographic pattern of individual muscles. Cellular responses of and within motor units and of muscles will be studied in an effort to define mechanisms that might play a role in the induction of the neuromuscular adaptations. These studies should provide further data suggesting that the clinical benefits of optimizing post-neural lesion care can be significant. Further, these studies should provide important data which identifies the features of the rehabilitation procedures that are particularly effective.